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34.1.6.4.4.2 Deprotonative Construction of a Carbon-Carbon Single Bond under an SN2 or SN2′ Mechanism

DOI: 10.1055/sos-SD-134-00125

Yamazaki, T.Science of Synthesis Knowledge Updates, (20172299.

As described in Section 34.1.6.4.4.1 (Scheme 15), fluorobis(phenylsulfonyl)methane is a versatile building block for the construction of a variety of fluorine-containing compounds by taking advantage of the easy removal of the phenylsulfonyl moiety. In the first reaction shown in Scheme 19, the hydroquinidine (anthraquinone-1,4-diyl) diether (52) undergoes SN2′-type reaction with acceptor acrylates, prepared by Morita–Baylis–Hillman reactions, followed by further SN2′-type reaction of fluorobis(phenylsulfonyl)methane in its anionic form with the formed intermediates. This allows formation of net SN2-type products 54 in high chemical and optical yields.[‌39‌] To improve the overall outcome of this process further, investigation into finding appropriate additives has led to the conclusion that the introduction of Lewis acids such as iron(II) chloride and titanium(IV) isopropoxide is effective to some extent owing to the formation of a bidentate chelate with fluorobis(phenylsulfonyl)methane, which plays an important role in locking the conformation; this is supported by a downfield shift in the signal for the methine proton in the 1H NMR spectrum. An analogous, independent study employing the exact same reactants and base catalyst, but with the use of mesitylene as the solvent and a reaction temperature of 30 °C, reports the formation of products 54 in yields of 71 to 99% with 90–97% ee.[‌40‌] Exchange of the solvent to toluene has also been shown to be an easy method to improve the optical purity of 54 to almost perfect.

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M8 Meeeeeee ee (%) Meeee (%) Mee
Me 88 88 [‌88‌]
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Me >88.8 88e [‌88‌]
8-MeM8M8 88 88 [‌88‌]
8-MeM8M8 MeMe8 88 88 [‌88‌]
8-MeM8M8 Me(MeMe)8 88 88 [‌88‌]
8-MeM8M8 88 88 [‌88‌]
8-MeM8M8 MeMe8 88 88 [‌88‌]
8-MeM8M8 Me(MeMe)8 88 88 [‌88‌]
8-MeM8M8 88 88 [‌88‌]
8-MeM8M8 MeMe8 88 88 [‌88‌]
8-MeM8M8 Me(MeMe)8 88 88 [‌88‌]
8-Mee 88 88 [‌88‌]
8-Mee MeMe8 88 88 [‌88‌]
8-Mee Me(MeMe)8 88 88 [‌88‌]
8-M8MM8M8 88 88 [‌88‌]
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8-M8MM8M8 Me(MeMe)8 88 88 [‌88‌]

e Meeeeeee eee eeeeeeeee ee eeeeeeeeee ee 88 °M eee 88 e.

e Meeeeeee eee eeeeeeeee ee eeeeeee ee 88 °M eee 88 e.

M8 ee (%) Meeee (%) Mee
Me 88 88 [‌88‌]
8-MeMM8M8 88 88 [‌88‌]
8-MeM8M8 88 88 [‌88‌]
8-eeeeeeee 88 88 [‌88‌]
8-eMeM8M8 88 88 [‌88‌]

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Meeeee 88 Meeeeeee ee Meeeeeeee(eeeeeeeeeeeeee)eeeeeee eeee 8-Meeeeeeee-8,8-eeeeee[‌88‌]

Meeeeeeeeee 88

M8 M8 M8 Meeee (%) Mee
Me M M 88 [‌88‌]
e-Me M M 88 [‌88‌]
(MM8)8Me M M 88 [‌88‌]
8-MeMM8M8 M M 88 [‌88‌]
8-M8MM8M8 M M 88 [‌88‌]
Me Me Me 88 [‌88‌]
Me Me M 88 [‌88‌]

Meeeeeeeeeee Meeeeeeee

Meeeee (8M)-8-Meeeee-8-eeeeeeeee-8-eeeeee-8,8-eee(eeeeeeeeeeeeee)eeeeeeeee [(M)-88, M8 = Me]; Meeeeee Meeeeeeee:[‌88‌]

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8-Meeeeeeeeee 8-Meeeee-8,8-eee(eeeeeeeeeeeeee)eeeee-8,8-eeeeee 88; Meeeeee Meeeeeeee:[‌88‌]

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